Call number: LD2668 .T4 1985 Y37 / Master of Science

This M.A. thesis makes use of the concept and methodology of vulnerability, ‘state capacity’ theory, and Robert Wade’s ‘Wheels Within Wheels’ argument to assess the role of China within the modern global economy. The thesis draws upon the repeated identification of China as a possible global systemic risk by the World Economic Forum’s Global Risk Network as a starting point, with the goal of determining why and how China would be identified in such a way, what elements support such an identification, and to what extent China’s economy might indeed represent a source of vulnerability in the global economic system. The thesis analyzes two key Chinese economic sectors: currency and reserve policy, and the domestic banking sector. Six broad vulnerability vectors are ultimately identified. The thesis concludes that, while China may represent a source of vulnerability in the global economy, it also represents a potentially strong source of resilience due to its unique economic system that emphasizes the role of the state.

Thesis: M.S., Massachusetts Institute of Technology, Department of Civil Engineering, 1981 / Includes bibliographical references. / by Sacha Sethaputra. / M.S. / M.S. Massachusetts Institute of Technology, Department of Civil Engineering

This thesis reports the investigation into the modelling and simulation of an aircraft tyre and wheel assembly in finite element environment. The finite element simulations basing on aircraft tyre test and operational scenarios could predict the loads transferred from tyre and the stresses distributed to the wheel rim. The virtual analysis could assess the safety criteria of different tyre structures, which would lead to the cost and time circle reduction in tyre R&D process. An H41x16.0R20 radial ply aircraft test tyre and its corresponding test wheel, provided by Dunlop Aircraft Tyres Limited, are adopted as the subject of this research. The material properties, especially the rubber and fabric materials, have been investigated. The finite element hyperelastic models have been utilized to represent rubbers and been correlated to experimental data. The 2D and 3D finite element tyre models, along with the finite element wheel models are created in the commercial finite element code, LS-Dyna. The finite element models have been validated with either industrial standardised simulation results or experimental data. Basing on the validated models, simulations that duplicating static test and dynamic operational scenarios have been developed. The researches have provided knowledge in comparing single and double bead tyre designs with respect to wheel loading mechanisms. The computational model also allowed manufacturers to assess the performance and safety criteria of a particular tyre at its design stage. The development of such models would add to the general drive towards the use of more virtual prototypes in an area traditionally reliant on experimental testing.

This work investigates threshold forces and vibrations in diamond roll plunge dressing of vitreous bonded aluminum oxide grinding wheels. Threshold forces in dressing are not currently considered in the control of the dress cycles of grinding wheels in manufacturing. These threshold forces, however, can lead to size, taper, and out of round errors on the grinding wheel, which are then imparted onto the workpiece. Particularly in internal grinding, and other setups with lower spindle stiffnesses, any threshold force in dressing will cause deflection of the spindle before removing abrasive, which will lead to the grinding wheel being out of size. Hall-effect sensors on the grinding wheel spindle are used to determine the normal force, and a linear encoder on the dressing roll cross-slide is used to determine the abrasive removal rate. The abrasive removal rate is plotted against the normal force for a number of feedrates, and two distinct slopes were observed, with two different threshold forces. In addition, an acoustic emission system is compared to the hall-effect force sensor to study the correlation of the two sensors.

It is expected that by 2030, nearly 21% of the population will consist of older adults, aged 65 years and older. Those who reach 65 have an average life expectancy of an additional 19 years. Adequate nutrition is essential to health and quality of life, especially for older adults. Congregate and home-delivered meal programs are an ideal setting in which to provide nutrition education for older adults that can lead to increases in successful aging. This cross-sectional study involved development and distribution of a novel survey for nutrition educators working with congregate and home-delivered meal programs. The purpose of this study was to describe the type and frequency of nutrition education provided by nutrition educators at congregate and home-delivered meal sites, whether lessons are behaviorally focused and theory-based, and which educator factors influence theory-based, behaviorally focused nutrition education score. The researcher also sought to examine if education sessions were being evaluated for effectiveness, if malnutrition was playing a role in nutrition education, whether state policies impact nutrition education, and if differences in nutrition education exist between dietetic and non-dietetic health professionals. Dietetic professionals (n = 122) are conducting more theory-based, behaviorally focused nutrition education (TB-BF-NE) than non-dietetic professionals (n = 139) (p < 0.001). A regression analysis showed that the educator factors predicting TB-BF-NE were number of topics taught, group size, length of session, and conducting evaluation (R2 = .518, p < 0.001). State policies on dietetic oversight did not appear to have an impact. Educators reported malnutrition was a major issue for older adults but did not feel they had the tools to screen for or address malnutrition. The most common topics for nutrition education were food safety, healthy eating, and diabetes; the most common delivery method was handouts. Because this is the first study of its kind, further exploration is indicated. Nutrition educators working with congregate and home-delivered meal participants need to be better trained on providing theory-based and behaviorally focused nutrition education, conducting evaluations, and finding materials and evidence-based lessons for older adults. Better training can also help educators implement more interactive lessons that will maintain the attention of the older adults they serve.

Orientador: Fernando de Azevedo Silva / Banca: João Zangrandi Filho / Banca: Anselmo Monteiro Ilkiu / Resumo: O objetivo desta pesquisa foi apresentar um método de análise para a solução de problemas de contato por elementos finitos e o cálculo dos componentes mecânicos que fazem parte do projeto de uma roda de aço. Foi demonstrado passo a passo à execução de um cálculo analítico da roda de uma Comporta Vagão, calculando as cargas radial e axial presentes, verificando a tensão de Hertz, as tensões localizadas no cubo da roda, as tensões atuantes no eixo e a seleção do rolamento. Após esta etapa retiraram-se os parâmetros iniciais que foram utilizados no cálculo analítico para buscar o cálculo por elementos finitos. Assim, foram definidas as superfícies de contato, a geometria dos componentes, a malha, as restrições, as condições de contorno e por fim a análise dos resultados encontrados antes e após o projeto. Dessa maneira, podê-se determinar com precisão os pontos de concentração de tensão para eliminação as falhas. Com a busca deste cálculo, usando a análise por Elementos Finitos, respaldado pelo cálculo analítico, foi possível reduzir o diâmetro da roda para obter ganhos em massa para este tipo de equipamento que usa uma quantidade alta de rodas (acima de 100 rodas), sem alteração da confiabilidade das peças durante seu funcionamento. / Abstract: The objective of this research was to present an analysis method for the solution of contact problems for finite elements and the calculation of the mechanical components that are part of the project of a steel wheel. It was demonstrated step by step the execution of an analytic calculation of the wheel of a Fixed Wheel Gate, calculating the radial and axial loads present, verifying the Hertz pressure, the concentrated stresses in the hub of the wheel, the acting stresses in the shaft and hub, and the selection of the roller bearings. After this stage the initial parameters were used in the analytic calculation in order to obtain the calculation using finite elements. After this, it was defined the contact surfaces, the geometry of the components, the mesh, the restrictions, the real constraints and finally the analysis of the results found before and after the project. After this calculation, the other analysis was established in order to determine the points of concentration stress accurately for the elimination of fails. In order to obtain the calculation, using Finite Elements, by the analytic calculation it was possible to reduce the diameter of the wheel to obtain earn in mass for this type of equipment that uses a high amount of wheels (above 100 wheels), without alteration of the reliability of the parts during the operation. / Mestre

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg 2016 / This investigation considers the influence of a three spring and damper suspension system (SDS) on overall vehicle performance. Three SDS systems are used in high performance winged racing cars to manage the effects of the aerodynamic forces. The aim of the investigation was to quantify and compare the performance of a three SDS system to that of a conventional two SDS system. The investigation was carried out on the Bailey Cars LMP2 race car. Physical track testing was conducted on Zwartkops Raceway to measure the vehicle’s performance, with further testing conducted on the vehicle’s tyres. A software model of the vehicle and tyres was then created in ADAMS/Car, with models for the conventional two SDS system, as well as the three SDS system. The ADAMS/Car model was then validated against the test data. A Design of Experiments approach was used to investigate the influence of the parameters in both the suspension models. The optimal set of suspension parameters, that maximised vehicle performance on Zwartkops Raceway, was then identified. The performance of the optimal suspension systems was then compared to quantify the effect of the three SDS system. It was found that the optimised three SDS system travelled 4.38 m less than the optimal two SDS in a 60 second simulation on Zwartkops Raceway. However, the three SDS was effectively able to isolate the pitch and roll stiffness of the vehicle. The optimal three SDS had a greater pitch stiffness and less roll stiffness than the two SDS. This is significant for winged vehicles where aerodynamic forces are highly sensitive to vehicle pitch, such as the Bailey Cars LMP2 race car, allowing for a soft wheel rate without sacrificing the pitch stiffness of the vehicle. / MT2017

Excerpt: "I'm crazy about trains! says Doc Holliday (Jason Robards) to his friend Wyatt Earp (James Garner) in Hour of the Gun (Sturges Ch. 6), explaining why he's waiting on the Contention train. Of course he's really there to help Earp get his revenge on Ike Clanton (Robert Ryan) - but then we never quite know with Doc Holliday.

This dissertation addresses rigid body attitude control with piecewise sinusoidal signals. We consider rigid-body attitude kinematics on SO(3) with a class of sinusoidal inputs. We present a new closed-form solution of the rotation matrix kinematics. The solution is analyzed and used to prove controllability. We then present kinematic-level orientation-feedback controllers for setpoint tracking and command following. Next, we extend the sinusoidal kinematic-level control to the dynamic level. As a representative dynamic system, we consider a CubeSat with vibrating momentum actuators that are driven by small $\epsilon$-amplitude piecewise sinusoidal internal torques. The CubeSat kinetics are derived using Newton-Euler's equations of motion. We assume there is no external forcing and the system conserves zero angular momentum. A second-order approximation of the CubeSat rotational motion on SO(3) is derived and used to derive a setpoint tracking controller that yields order O(ε2) closed-loop error. Numerical simulations are presented to demonstrate the performance of the controls. We also examine the effect of the external damping on the CubeSat kinetics. In addition, we investigate the feasibility of the piecewise sinusoidal control techniques using an experimental CubeSat system. We present the design of the CubeSat mechanical system, the control system hardware, and the attitude control software. Then, we present and discuss the experiment results of yaw motion control. Furthermore, we experimentally validate the analysis of the external damping effect on the CubeSat kinetics.